The overall goal of this core is to support the specific aims of the 4 projects with existing small animal[unreadable] imaging technology and to advance this technology to enhance future utility in cancer research. Small animal[unreadable] imaging has gained considerable importance in recent years as more and more animal models for human[unreadable] cancers have become available. Imaging of tumor development and effects of treatments has many scientific[unreadable] and economical advantages, as sacrificing animals at various disease stages and performing necropsy and[unreadable] histopathological studies can be sharply reduced. Optical techniques have proven to be especially valuable[unreadable] when applied to small animal imaging because of an abundance of optical markers (endogenous and[unreadable] exogenous) that can target and visualize various cancer related processes on the cellular and molecular[unreadable] level with comparatively high sensitivities. However, to date most optical imaging studies have only explored[unreadable] whole animal surface imaging without 3-dimensional reconstructions. This limits accurate localization and[unreadable] quantification of observed effects inside the animal.[unreadable] This core focuses on various optical imaging methods that can provide 3-dimensional functional[unreadable] information at high temporal resolution about blood-dependent parameters such as oxy, deoxy, and total[unreadable] hemoglobin, fluorescent markers such as GFP, and bioluminescent probes such as luciferase. Imaging[unreadable] system that will be made available include a two-photon microscope for high-spatial-resolution (<0.1 mu m up[unreadable] to depth of 600 mu m) imaging of hemodynamic effects and fluorescent probes in situ; two dynamic optical[unreadable] tomography devices and one frequency-domain optical tomography system for non-invasive whole-animal[unreadable] absorption imaging; and a Xenogen IVIS 200 system for whole-animal fluorescence and bioluminescence[unreadable] imaging. Together with a 9.4 T magnetic resonance imaging system, which delivers high-resolution anatomical[unreadable] images of small animals, the core will enable researcher to study effects of hypoxia on tumor development,[unreadable] migration of activated myofibroblasts, bone marrow recruitment, and tumor growth and regression.[unreadable] Going beyond applying existing optical technologies, the core will also advance imaging science in[unreadable] itself. First, we will develop novel, highly accurate, three-dimensional image reconstruction capabilities for[unreadable] the existing Xenogen IVIS 200 bioluminescence imager. Second, we will adapt and optimize laminar optical[unreadable] tomography (LOT) for applications in digestive cancer research. LOT promises to be a viable optical imaging[unreadable] modality that can provide absorption and fluorescence imaging of tissues to depths of 2-3mm with 100 to[unreadable] 200 mu m resolution. If successfully applied to cancer imaging, this modality would fill an important niche[unreadable] between the high-resolution two-photon microscope systems and the whole-animal optical imaging devices.[unreadable]